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ptrace.c

/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include "linux/audit.h"
#include "linux/ptrace.h"
#include "linux/sched.h"
#include "asm/uaccess.h"
#ifdef CONFIG_PROC_MM
#include "proc_mm.h"
#endif
#include "skas_ptrace.h"

static inline void set_singlestepping(struct task_struct *child, int on)
{
      if (on)
            child->ptrace |= PT_DTRACE;
      else
            child->ptrace &= ~PT_DTRACE;
      child->thread.singlestep_syscall = 0;

#ifdef SUBARCH_SET_SINGLESTEPPING
      SUBARCH_SET_SINGLESTEPPING(child, on);
#endif
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
      set_singlestepping(child,0);
}

extern int peek_user(struct task_struct * child, long addr, long data);
extern int poke_user(struct task_struct * child, long addr, long data);

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
      int i, ret;
      unsigned long __user *p = (void __user *)(unsigned long)data;

      switch (request) {
      /* read word at location addr. */
      case PTRACE_PEEKTEXT:
      case PTRACE_PEEKDATA:
            ret = generic_ptrace_peekdata(child, addr, data);
            break;

      /* read the word at location addr in the USER area. */
      case PTRACE_PEEKUSR:
            ret = peek_user(child, addr, data);
            break;

      /* write the word at location addr. */
      case PTRACE_POKETEXT:
      case PTRACE_POKEDATA:
            ret = generic_ptrace_pokedata(child, addr, data);
            break;

      /* write the word at location addr in the USER area */
      case PTRACE_POKEUSR:
            ret = poke_user(child, addr, data);
            break;

      /* continue and stop at next (return from) syscall */
      case PTRACE_SYSCALL:
      /* restart after signal. */
      case PTRACE_CONT: {
            ret = -EIO;
            if (!valid_signal(data))
                  break;

            set_singlestepping(child, 0);
            if (request == PTRACE_SYSCALL)
                  set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
            else clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
            child->exit_code = data;
            wake_up_process(child);
            ret = 0;
            break;
      }

/*
 * make the child exit.  Best I can do is send it a sigkill.
 * perhaps it should be put in the status that it wants to
 * exit.
 */
      case PTRACE_KILL: {
            ret = 0;
            if (child->exit_state == EXIT_ZOMBIE)     /* already dead */
                  break;

            set_singlestepping(child, 0);
            child->exit_code = SIGKILL;
            wake_up_process(child);
            break;
      }

      case PTRACE_SINGLESTEP: {  /* set the trap flag. */
            ret = -EIO;
            if (!valid_signal(data))
                  break;
            clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
            set_singlestepping(child, 1);
            child->exit_code = data;
            /* give it a chance to run. */
            wake_up_process(child);
            ret = 0;
            break;
      }

#ifdef PTRACE_GETREGS
      case PTRACE_GETREGS: { /* Get all gp regs from the child. */
            if (!access_ok(VERIFY_WRITE, p, MAX_REG_OFFSET)) {
                  ret = -EIO;
                  break;
            }
            for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
                  __put_user(getreg(child, i), p);
                  p++;
            }
            ret = 0;
            break;
      }
#endif
#ifdef PTRACE_SETREGS
      case PTRACE_SETREGS: { /* Set all gp regs in the child. */
            unsigned long tmp = 0;
            if (!access_ok(VERIFY_READ, p, MAX_REG_OFFSET)) {
                  ret = -EIO;
                  break;
            }
            for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
                  __get_user(tmp, p);
                  putreg(child, i, tmp);
                  p++;
            }
            ret = 0;
            break;
      }
#endif
#ifdef PTRACE_GETFPREGS
      case PTRACE_GETFPREGS: /* Get the child FPU state. */
            ret = get_fpregs((struct user_i387_struct __user *) data,
                         child);
            break;
#endif
#ifdef PTRACE_SETFPREGS
      case PTRACE_SETFPREGS: /* Set the child FPU state. */
              ret = set_fpregs((struct user_i387_struct __user *) data,
                         child);
            break;
#endif
      case PTRACE_GET_THREAD_AREA:
            ret = ptrace_get_thread_area(child, addr,
                                   (struct user_desc __user *) data);
            break;

      case PTRACE_SET_THREAD_AREA:
            ret = ptrace_set_thread_area(child, addr,
                                   (struct user_desc __user *) data);
            break;

      case PTRACE_FAULTINFO: {
            /*
             * Take the info from thread->arch->faultinfo,
             * but transfer max. sizeof(struct ptrace_faultinfo).
             * On i386, ptrace_faultinfo is smaller!
             */
            ret = copy_to_user(p, &child->thread.arch.faultinfo,
                           sizeof(struct ptrace_faultinfo));
            break;
      }

#ifdef PTRACE_LDT
      case PTRACE_LDT: {
            struct ptrace_ldt ldt;

            if (copy_from_user(&ldt, p, sizeof(ldt))) {
                  ret = -EIO;
                  break;
            }

            /*
             * This one is confusing, so just punt and return -EIO for
             * now
             */
            ret = -EIO;
            break;
      }
#endif
#ifdef CONFIG_PROC_MM
      case PTRACE_SWITCH_MM: {
            struct mm_struct *old = child->mm;
            struct mm_struct *new = proc_mm_get_mm(data);

            if (IS_ERR(new)) {
                  ret = PTR_ERR(new);
                  break;
            }

            atomic_inc(&new->mm_users);
            child->mm = new;
            child->active_mm = new;
            mmput(old);
            ret = 0;
            break;
      }
#endif
#ifdef PTRACE_ARCH_PRCTL
      case PTRACE_ARCH_PRCTL:
            /* XXX Calls ptrace on the host - needs some SMP thinking */
            ret = arch_prctl(child, data, (void *) addr);
            break;
#endif
      default:
            ret = ptrace_request(child, request, addr, data);
            if (ret == -EIO)
                  ret = subarch_ptrace(child, request, addr, data);
            break;
      }

      return ret;
}

void send_sigtrap(struct task_struct *tsk, struct uml_pt_regs *regs,
              int error_code)
{
      struct siginfo info;

      memset(&info, 0, sizeof(info));
      info.si_signo = SIGTRAP;
      info.si_code = TRAP_BRKPT;

      /* User-mode eip? */
      info.si_addr = UPT_IS_USER(regs) ? (void __user *) UPT_IP(regs) : NULL;

      /* Send us the fake SIGTRAP */
      force_sig_info(SIGTRAP, &info, tsk);
}

/*
 * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
 * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
 */
void syscall_trace(struct uml_pt_regs *regs, int entryexit)
{
      int is_singlestep = (current->ptrace & PT_DTRACE) && entryexit;
      int tracesysgood;

      if (unlikely(current->audit_context)) {
            if (!entryexit)
                  audit_syscall_entry(HOST_AUDIT_ARCH,
                                  UPT_SYSCALL_NR(regs),
                                  UPT_SYSCALL_ARG1(regs),
                                  UPT_SYSCALL_ARG2(regs),
                                  UPT_SYSCALL_ARG3(regs),
                                  UPT_SYSCALL_ARG4(regs));
            else audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
                              UPT_SYSCALL_RET(regs));
      }

      /* Fake a debug trap */
      if (is_singlestep)
            send_sigtrap(current, regs, 0);

      if (!test_thread_flag(TIF_SYSCALL_TRACE))
            return;

      if (!(current->ptrace & PT_PTRACED))
            return;

      /*
       * the 0x80 provides a way for the tracing parent to distinguish
       * between a syscall stop and SIGTRAP delivery
       */
      tracesysgood = (current->ptrace & PT_TRACESYSGOOD);
      ptrace_notify(SIGTRAP | (tracesysgood ? 0x80 : 0));

      if (entryexit) /* force do_signal() --> is_syscall() */
            set_thread_flag(TIF_SIGPENDING);

      /*
       * this isn't the same as continuing with a signal, but it will do
       * for normal use.  strace only continues with a signal if the
       * stopping signal is not SIGTRAP.  -brl
       */
      if (current->exit_code) {
            send_sig(current->exit_code, current, 1);
            current->exit_code = 0;
      }
}

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